I'm aware that in Europe, most carriers use kilograms to measure aircraft and fuel weights. Is this the same in the US, or do pilots use pounds to measure weights?

Well I'm Canadian so I could be wrong. But as far as I know the U.S. still uses the imperial system(lbs.) for everything. If they are travelling to Canada or Europe maybe they need to convert. But I'm sure in the U.S. it's all imperial.

The U.S. Cargo carriers - Atlas and Polar Air utilize KGS. all the other major U.S. carriers use LBS as far as I know.